The present invention relates to a process for treating perfluorides (or perfluorocompounds), more particularly to a process for treating perfluorides released from semiconductor manufacturing plants and liquid crystal producing plants.
Technical renovation of semiconductor industries advances so rapidly that alternation of generations takes place in two to four years in this field of industries. This calls for the introduction of up-to-date equipment for fining works which can measure up to the advance of manufacturing techniques corresponding to the alternation of generations of semiconductors. The semiconductor makers, therefore, always feel the necessity of introduction of the newest semiconductor manufacturing equipment.
In the semiconductor (semiconductor chip and liquid crystal panel) manufacturing plants, perfluorocompounds are used as etching gas or cleaning gas in the semiconductor manufacturing steps. Perfluorocompounds (hereinafter referred to as PFC) are a general term for the chlorine-free compounds of carbon and fluorine, carbon, hydrogen and fluorine, sulfur and fluorine, and nitrogen and fluorine, such as CF4, CHF3, C2F6, CH2F2, C3F8, C5C8, SF6 and NF3. PFC have a long life time in the atmosphere (10,000 years for C2F6 and 3,200 years for SF6), and they are an earth warming gas with a large warming factor, so that their release into the atmosphere is regulated. Researchers are pursuing studies on the method of decomposing PFC. In one PFC decomposition technique PFC are hydrolyzed by making use of a catalyst, and the discharge gas containing the hydrolyzate gas is washed with water (or an alkaline solution) and then released to the atmosphere by using exhaust equipment (blower or ejector).
As means for the decomposition of PFC, beside the said technique using a catalyst, there are also known a combustion method in which PFC are decomposed by combustion, and a plasma method in which PFC are decomposed by turning them into plasma.
The semiconductor makers will be obliged to make an investment in introduction of PFC decomposition treating apparatus as an environmental protection measure, in addition to a vast investment for the latest semiconductor manufacturing plant. However, they are not allowed to remain indifferent to decomposition treatment of PFC released from the semiconductor manufacturing plants, which is an important environmental protection measure, only for the reason that a huge investment is required for the semiconductor manufacturing plant.